U. H. Gysel of the Stanford Research Center disclosed a device in his paper entitled "A New N-Way Power Divider/Combiner Suitable for High Power Amplifications" which appeared in the proceedings of the 1975 M.T.T. Symposium in Palo Alto, Calif. The Gysel device is discussed in the introduction of the U.S. Pat. No. to F. W. Iden 4,163,955. Iden pointed out that the Gysel device offered external isolation loads (high power load resistors) and monitoring capability for imbalances at the output/input ports and, as such, is an improvement over another prior art combiner/divider known as the Wilkinson device. Iden pointed out that Gysel offered no means for practical realization of his device other than pointing out that its construction could take the form of either stripline, slabline or microstrip.
Iden, in his patent, stated that an attempt to implement the Gysel device resulted in a sandwich-type structure employing stripline to provide the required quarter wavelength transmission lines. This was apparently realized on a Teflon board in microstrip form. Apparently, two separate boards were used and, through connections, necessitated by the topology of the design, were made with one millimeter bolts. The foregoing description, found in the Iden patent, does not present a disclosure of how the two boards are interconnected or whether or not the boards are parallel to each other or whether they are oriented in an over and under layered three dimensional arrangement. Iden's patent presents a modification of the Gysel circuit with a radial cylindrical structure which appears quite awkward from the standpoint of size and assembly. It is believed that a five kilowatt 100 MHz application of the Iden structure for a five-way combining system would require an assembly of over six feet tall. Moreover, the Gysel modified circuit presented by the Iden patent requires substantial use of coaxial cable interconnections including interconnections to external loads that are vital to circuit performance.
It has been determined that by implementing a Gysel type circuit in a three dimensional layered structure, one may provide high power handling capability in a mechanically compact unit. For example, a five kilowatt 100 MHz application for a five-way combining system could be assembled as a layered three dimensional structure having dimensions on the order of two feet square and less than one foot thick. Moreover, such a device could take the form of a complete combiner assembly having reject loads as an integral assembly.
Moreover, a Gysel type circuit as discussed in the Iden patent has a relatively narrow bandwidth for acceptable input port return loss operation. It is therefore desirable to improve upon the Gysel device in such a way as to increase its bandwidth performance so that relatively good impedance matching may take place over a bandwidth over a range from, for example, 87.5 MHz to 108 MHz.